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Command: alloc logs

Alias: nomad logs

The alloc logs command displays the log of a given task.

Usage

nomad alloc logs [options] <allocation> <task>

This command streams the logs of the given task in the allocation. If the allocation is only running a single task, the task name can be omitted. Optionally, the -job option may be used in which case a random allocation from the given job will be chosen.

Task name may also be specified using the -task option rather than a command argument. If task name is given with both an argument and the -task option, preference is given to the -task option.

When ACLs are enabled, this command requires a token with the read-logs, read-job, and list-jobs capabilities for the allocation's namespace.

General Options

  • -address=<addr>: The address of the Nomad server. Overrides the NOMAD_ADDR environment variable if set. Defaults to http://127.0.0.1:4646.

  • -region=<region>: The region of the Nomad server to forward commands to. Overrides the NOMAD_REGION environment variable if set. Defaults to the Agent's local region.

  • -namespace=<namespace>: The target namespace for queries and actions bound to a namespace. Overrides the NOMAD_NAMESPACE environment variable if set. If set to '*', subcommands which support this functionality query all namespaces authorized to user. Defaults to the "default" namespace.

  • -no-color: Disables colored command output. Alternatively, NOMAD_CLI_NO_COLOR may be set. This option takes precedence over -force-color.

  • -force-color: Forces colored command output. This can be used in cases where the usual terminal detection fails. Alternatively, NOMAD_CLI_FORCE_COLOR may be set. This option has no effect if -no-color is also used.

  • -ca-cert=<path>: Path to a PEM encoded CA cert file to use to verify the Nomad server SSL certificate. Overrides the NOMAD_CACERT environment variable if set.

  • -ca-path=<path>: Path to a directory of PEM encoded CA cert files to verify the Nomad server SSL certificate. If both -ca-cert and -ca-path are specified, -ca-cert is used. Overrides the NOMAD_CAPATH environment variable if set.

  • -client-cert=<path>: Path to a PEM encoded client certificate for TLS authentication to the Nomad server. Must also specify -client-key. Overrides the NOMAD_CLIENT_CERT environment variable if set.

  • -client-key=<path>: Path to an unencrypted PEM encoded private key matching the client certificate from -client-cert. Overrides the NOMAD_CLIENT_KEY environment variable if set.

  • -tls-server-name=<value>: The server name to use as the SNI host when connecting via TLS. Overrides the NOMAD_TLS_SERVER_NAME environment variable if set.

  • -tls-skip-verify: Do not verify TLS certificate. This is highly not recommended. Verification will also be skipped if NOMAD_SKIP_VERIFY is set.

  • -token: The SecretID of an ACL token to use to authenticate API requests with. Overrides the NOMAD_TOKEN environment variable if set.

Logs Options

  • -stdout: Display stdout logs. This is used as the default value in all commands except when using the -f flag where both stdout and stderr are used as default.

  • -stderr: Display stderr logs.

  • -verbose: Display verbose output.

  • -job: Use a random allocation from the specified job or job ID prefix, preferring a running allocation.

  • -task: Specify the task to view the logs.

  • -f: Causes the output to not stop when the end of the logs are reached, but rather to wait for additional output. When supplied with no other flags except optionally -job and -task, both stdout and stderr logs will be followed.

  • -tail: Show the logs contents with offsets relative to the end of the logs. If no offset is given, -n is defaulted to 10.

  • -n: Sets the tail location in best-efforted number of lines relative to the end of the logs.

  • -c: Sets the tail location in number of bytes relative to the end of the logs.

Note that the -no-color option applies to Nomad's own output. If the task's logs include terminal escape sequences for color codes, Nomad will not remove them.

Examples

$ nomad alloc logs eb17e557 redis
foobar
baz
bam

$ nomad alloc logs -stderr eb17e557 redis
[ERR]: foo
[ERR]: bar

$ nomad alloc logs -job example
[ERR]: foo
[ERR]: bar

$ nomad alloc logs -tail -n 2 eb17e557 redis
foobar
baz

$ nomad alloc logs -tail -f -n 3 eb17e557 redis
foobar
baz
bam
<blocking>

Specifying task name with the -task option:

$ nomad alloc logs -task redis eb17e557

If task name is specified using both options, the command argument is ignored. The following will output the logs from the "redis" task only, not the "api" task:

$ nomad alloc logs -task redis eb17e557 api

Using Job ID instead of Allocation ID

Setting the -job flag causes a random allocation of the specified job to be selected. Nomad will prefer to select a running allocation ID for the job, but if no running allocations for the job are found, Nomad will use a dead allocation.

nomad alloc logs -job <job-id> <task>

Choosing a specific allocation is useful for debugging issues with a specific instance of a service. For other operations using the -job flag may be more convenient than looking up an allocation ID to use.