docs: learn/advance (#22367)
This commit is contained in:
Julián Toledano
@@ -37,13 +37,13 @@ The `main.go` file needs to have a `main()` function that creates a root command
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* **setting configurations** by reading in configuration files (e.g. the Cosmos SDK config file).
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* **adding any flags** to it, such as `--chain-id`.
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* **instantiating the `codec`** by injecting the application codecs. The [`codec`](https://docs.cosmos.network/main/learn/advanced/encoding) is used to encode and decode data structures for the application - stores can only persist `[]byte`s so the developer must define a serialization format for their data structures or use the default, Protobuf.
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* **instantiating the `codec`** by injecting the application codecs. The [`codec`](./05-encoding.md) is used to encode and decode data structures for the application - stores can only persist `[]byte`s so the developer must define a serialization format for their data structures or use the default, Protobuf.
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* **adding subcommand** for all the possible user interactions, including [transaction commands](#transaction-commands) and [query commands](#query-commands).
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The `main()` function finally creates an executor and [execute](https://pkg.go.dev/github.com/spf13/cobra#Command.Execute) the root command. See an example of `main()` function from the `simapp` application:
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```go reference
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https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/simapp/simd/main.go#L12-L24
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https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.2/simapp/simd/main.go#L14-L20
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```
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The rest of the document will detail what needs to be implemented for each step and include smaller portions of code from the `simapp` CLI files.
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@@ -57,16 +57,16 @@ Every application CLI first constructs a root command, then adds functionality b
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The root command (called `rootCmd`) is what the user first types into the command line to indicate which application they wish to interact with. The string used to invoke the command (the "Use" field) is typically the name of the application suffixed with `-d`, e.g. `simd` or `gaiad`. The root command typically includes the following commands to support basic functionality in the application.
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* **Status** command from the Cosmos SDK rpc client tools, which prints information about the status of the connected [`Node`](./03-node.md). The Status of a node includes `NodeInfo`,`SyncInfo` and `ValidatorInfo`.
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* **Keys** [commands](https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/client/keys) from the Cosmos SDK client tools, which includes a collection of subcommands for using the key functions in the Cosmos SDK crypto tools, including adding a new key and saving it to the keyring, listing all public keys stored in the keyring, and deleting a key. For example, users can type `simd keys add <name>` to add a new key and save an encrypted copy to the keyring, using the flag `--recover` to recover a private key from a seed phrase or the flag `--multisig` to group multiple keys together to create a multisig key. For full details on the `add` key command, see the code [here](https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/client/keys/add.go). For more details about usage of `--keyring-backend` for storage of key credentials look at the [keyring docs](https://docs.cosmos.network/main/user/run-node/keyring).
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* **Keys** [commands](https://github.com/cosmos/cosmos-sdk/tree/v0.52.0-beta.2/client/keys) from the Cosmos SDK client tools, which includes a collection of subcommands for using the key functions in the Cosmos SDK crypto tools, including adding a new key and saving it to the keyring, listing all public keys stored in the keyring, and deleting a key. For example, users can type `simd keys add <name>` to add a new key and save an encrypted copy to the keyring, using the flag `--recover` to recover a private key from a seed phrase or the flag `--multisig` to group multiple keys together to create a multisig key. For full details on the `add` key command, see the code [here](https://github.com/cosmos/cosmos-sdk/tree/v0.52.0-beta.2/client/keys/add.go). For more details about usage of `--keyring-backend` for storage of key credentials look at the [keyring docs](https://docs.cosmos.network/main/user/run-node/keyring).
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* **Server** commands from the Cosmos SDK server package. These commands are responsible for providing the mechanisms necessary to start an ABCI CometBFT application and provides the CLI framework (based on [cobra](https://github.com/spf13/cobra)) necessary to fully bootstrap an application. The package exposes two core functions: `StartCmd` and `ExportCmd` which creates commands to start the application and export state respectively.
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Learn more [here](https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/server).
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Learn more [here](https://github.com/cosmos/cosmos-sdk/tree/v0.52.0-beta.2/server).
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* [**Transaction**](#transaction-commands) commands.
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* [**Query**](#query-commands) commands.
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Next is an example `rootCmd` function from the `simapp` application. It instantiates the root command, adds a [*persistent* flag](#flags) and `PreRun` function to be run before every execution, and adds all of the necessary subcommands.
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```go reference
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https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/simapp/simd/cmd/root_v2.go#L47-L130
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https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.2/simapp/simd/cmd/root_di.go#L32-L97
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```
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:::tip
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@@ -79,19 +79,19 @@ Read more about [AutoCLI](https://docs.cosmos.network/main/core/autocli) in its
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Here's an example code to override default `app.toml` template.
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```go reference
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https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/simapp/simd/cmd/root_v2.go#L144-L199
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https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.2/simapp/simd/cmd/config.go#L71-L125
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```
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The `initAppConfig()` also allows overriding the default Cosmos SDK's [server config](https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/server/config/config.go#L235). One example is the `min-gas-prices` config, which defines the minimum gas prices a validator is willing to accept for processing a transaction. By default, the Cosmos SDK sets this parameter to `""` (empty string), which forces all validators to tweak their own `app.toml` and set a non-empty value, or else the node will halt on startup. This might not be the best UX for validators, so the chain developer can set a default `app.toml` value for validators inside this `initAppConfig()` function.
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The `initAppConfig()` also allows overriding the default Cosmos SDK's [server config](https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.2/server/config/config.go). One example is the `min-gas-prices` config, which defines the minimum gas prices a validator is willing to accept for processing a transaction. By default, the Cosmos SDK sets this parameter to `""` (empty string), which forces all validators to tweak their own `app.toml` and set a non-empty value, or else the node will halt on startup. This might not be the best UX for validators, so the chain developer can set a default `app.toml` value for validators inside this `initAppConfig()` function.
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```go reference
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https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/simapp/simd/cmd/root_v2.go#L164-L180
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https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.2/simapp/simd/cmd/config.go#L41-L57
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```
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By default the app uses CometBFT app config template from Cosmos SDK, which can also be over-written via `initCometBFTConfig()`.
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```go reference
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https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/simapp/simd/cmd/root_v2.go#L132-L142
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https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.2/simapp/simd/cmd/config.go#L13-L26
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```
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Those custom templates and config must be provided to the `server.InterceptConfigsPreRunHandler` command in the `PersistentPreRunE` function of the root command. See [configuration](#configurations) section for more details.
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@@ -99,13 +99,13 @@ Those custom templates and config must be provided to the `server.InterceptConfi
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Additionally, like the `app.toml` and `config.toml`, the `client.toml` config can be extended or over-written by the user thanks to the `client.CreateClientConfig` function. This is useful for setting default values for the client without having to pass a flag. For example, the Cosmos SDK sets the default `keyring-backend` to `os` but the chain developer might instead want to always set it to `file` by default.
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```go reference
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https://github.com/cosmos/cosmos-sdk/blob/bb23e920676096b9fd2d2196daec389ad7f8192e/simapp/simd/cmd/root_v2.go#L78-L82
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https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.2/simapp/simd/cmd/root_di.go#L69-L73
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```
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Creating the custom template can be done in a `initClientConfig()` function.
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```go reference
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https://github.com/cosmos/cosmos-sdk/blob/bb23e920676096b9fd2d2196daec389ad7f8192e/simapp/simd/cmd/config.go#L24-L64
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https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.2/simapp/simd/cmd/config.go#L59-L66
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```
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The root-level `status` and `keys` subcommands are common across most applications and do not interact with application state. The bulk of an application's functionality - what users can actually *do* with it - is enabled by its `tx` and `query` commands.
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@@ -115,19 +115,19 @@ The root-level `status` and `keys` subcommands are common across most applicatio
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[Transactions](./01-transactions.md) are objects wrapping [`Msg`s](../../build/building-modules/02-messages-and-queries.md#messages) that trigger state changes. To enable the creation of transactions using the CLI interface, a function `txCommand` is generally added to the `rootCmd`:
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```go reference
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https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/simapp/simd/cmd/root_v2.go#L222-L229
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https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.2/simapp/simd/cmd/commands.go#L50-L58
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```
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This `txCommand` function adds all the transaction available to end-users for the application. This typically includes:
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* **Sign command** from the [`auth`](https://docs.cosmos.network/main/build/modules/auth) module that signs messages in a transaction. To enable multisig, add the `auth` module's `MultiSign` command. Since every transaction requires some sort of signature in order to be valid, the signing command is necessary for every application.
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* **Broadcast command** from the Cosmos SDK client tools, to broadcast transactions.
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* **All [module transaction commands](../../build/building-modules/09-module-interfaces.md#transaction-commands)** the application is dependent on, retrieved by using the [basic module manager's](../../build/building-modules/01-module-manager.md#basic-manager) `AddTxCommands()` function, or enhanced by [AutoCLI](https://docs.cosmos.network/main/core/autocli).
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* **All [module transaction commands](../../build/building-modules/09-module-interfaces.md#transaction-commands)** the application is dependent on, retrieved by using the [basic module manager's](../../build/building-modules/01-module-manager.md#module-manager) `AddTxCommands()` function, or enhanced by [AutoCLI](https://docs.cosmos.network/main/core/autocli).
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Here is an example of a `txCommand` aggregating these subcommands from the `simapp` application:
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```go reference
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https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/simapp/simd/cmd/root_v2.go#L270-L292
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https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.2/simapp/simd/cmd/commands.go#L92-L114
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```
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:::tip
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@@ -140,7 +140,7 @@ Read more about [AutoCLI](https://docs.cosmos.network/main/core/autocli) in its
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[**Queries**](../../build/building-modules/02-messages-and-queries.md#queries) are objects that allow users to retrieve information about the application's state. To enable the creation of queries using the CLI interface, a function `queryCommand` is generally added to the `rootCmd`:
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```go reference
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https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/simapp/simd/cmd/root_v2.go#L222-L229
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https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.2/simapp/simd/cmd/commands.go#L50-L58
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```
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This `queryCommand` function adds all the queries available to end-users for the application. This typically includes:
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@@ -149,12 +149,12 @@ This `queryCommand` function adds all the queries available to end-users for the
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* **Account command** from the `auth` module, which displays the state (e.g. account balance) of an account given an address.
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* **Validator command** from the Cosmos SDK rpc client tools, which displays the validator set of a given height.
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* **Block command** from the Cosmos SDK RPC client tools, which displays the block data for a given height.
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* **All [module query commands](../../build/building-modules/09-module-interfaces.md#query-commands)** the application is dependent on, retrieved by using the [basic module manager's](../../build/building-modules/01-module-manager.md#basic-manager) `AddQueryCommands()` function, or enhanced by [AutoCLI](https://docs.cosmos.network/main/core/autocli).
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* **All [module query commands](../../build/building-modules/09-module-interfaces.md#query-commands)** the application is dependent on, retrieved by using the [basic module manager's](../../build/building-modules/01-module-manager.md#module-manager) `AddQueryCommands()` function, or enhanced by [AutoCLI](https://docs.cosmos.network/main/core/autocli).
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Here is an example of a `queryCommand` aggregating subcommands from the `simapp` application:
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```go reference
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https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/simapp/simd/cmd/root_v2.go#L249-L268
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https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.2/simapp/simd/cmd/commands.go#L70-L90
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```
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:::tip
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@@ -168,7 +168,7 @@ Flags are used to modify commands; developers can include them in a `flags.go` f
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A *persistent* flag (as opposed to a *local* flag) added to a command transcends all of its children: subcommands will inherit the configured values for these flags. Additionally, all flags have default values when they are added to commands; some toggle an option off but others are empty values that the user needs to override to create valid commands. A flag can be explicitly marked as *required* so that an error is automatically thrown if the user does not provide a value, but it is also acceptable to handle unexpected missing flags differently.
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Flags are added to commands directly (generally in the [module's CLI file](../../build/building-modules/09-module-interfaces.md#flags) where module commands are defined) and no flag except for the `rootCmd` persistent flags has to be added at application level. It is common to add a *persistent* flag for `--chain-id`, the unique identifier of the blockchain the application pertains to, to the root command. Adding this flag can be done in the `main()` function. Adding this flag makes sense as the chain ID should not be changing across commands in this application CLI.
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Flags are added to commands directly (generally in the [module's CLI file](../../build/building-modules/09-module-interfaces.md#transaction-commands) where module commands are defined) and no flag except for the `rootCmd` persistent flags has to be added at application level. It is common to add a *persistent* flag for `--chain-id`, the unique identifier of the blockchain the application pertains to, to the root command. Adding this flag can be done in the `main()` function. Adding this flag makes sense as the chain ID should not be changing across commands in this application CLI.
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## Environment variables
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@@ -198,7 +198,7 @@ It is vital that the root command of an application uses `PersistentPreRun()` co
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Here is an example of an `PersistentPreRun()` function from `simapp`:
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```go reference
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https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/simapp/simd/cmd/root_v2.go#L81-L120
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https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.2/simapp/simd/cmd/root_di.go#L54-L84
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```
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The `SetCmdClientContextHandler` call reads persistent flags via `ReadPersistentCommandFlags` which creates a `client.Context` and sets that on the root command's `Context`.
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