support volume_mount in task

[lisongmin]

support volume_mount which defined in https://www.nomadproject.io/docs/job-specification/volume_mount

inspired from docker dirver.

[shishir-a412ed]

@lisongmin We already support volume, bind, and tmpfs mounts.
Code reference: buildMountpoint

Can you elaborate on what this PR is adding, which is currently missing in the driver?

[github-actions]

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[lisongmin]

@lisongmin We already support volume, bind, and tmpfs mounts.
Code reference: buildMountpoint

Can you elaborate on what this PR is adding, which is currently missing in the driver?

There are two ways to describe mount in nomad:

1. specified the mounts via driver's config:

   task "mysql-server" {
     driver = "containerd-driver"
   
     env = {
       "MYSQL_ROOT_PASSWORD" = "password"
     }
   
     config {
       image = "hashicorp/mysql-portworx-demo:latest"
   
     mounts = [ {
       type = "bind"
       source      = "/mysql"
       target = "/var/lib/mysql"
       options   = ["ro"]
     }]
   
       port_map {
         db = 3306
       }
     }
   }
   

2. specified the mounts via task's volume_mount:

   task "mysql-server" {
     driver = "containerd-driver"
   
     volume_mount {
       volume      = "mysql"
       destination = "/var/lib/mysql"
       read_only   = false
     }
   
     env = {
       "MYSQL_ROOT_PASSWORD" = "password"
     }
   
     config {
       image = "hashicorp/mysql-portworx-demo:latest"
   
       port_map {
         db = 3306
       }
     }
   }
   

and the later one is not supported by this plugin now.

[lisongmin]

I have read the CLA Document and I hereby sign the CLA

[shishir-a412ed]

@lisongmin Why do you need (2) when both (1) and (2) are doing the same thing?

[lisongmin]

No, it's not necessary.

But it's better to support it since there are many(some?) tutorials use the volume_mount option. and reduce people to debug the problem why not mounted.

Maybe keep compatible to docker is also a good reason?

[shishir-a412ed]

@lisongmin okay, Can you add an integration test with a task volume_mount (2) example?

The integration tests use the jobs defined in the example dir

You can add a new job in the example dir and use that to add an integration test.

The PR might need a rebase as well.

Thank you for the contributions 🙂

[shishir-a412ed]

@lisongmin Okay I think we have a bigger problem 🙂.

The agent.hcl is used by both the vagrant setup and tests setup

Currently, this will break the vagrant setup since there is no path /tmp/host_volume/s1 on the host. The path is only setup as part of the tests. Vagrant setup is mostly for users who want to quickly bring a vagrant VM up (with all the necessary dependencies installed e.g. containerd, containerd-driver) and manually try out a few jobs.

I think we should separate the example/agent.hcl for the two use-cases.

Can we:

1. Create a separate example/agent_tests.hcl which is a copy of example/agent.hcl +

client {
   host_volume "s1" {
     path = "/tmp/host_volume/s1"
     read_only = false
   }
 }

2. Change run_tests.sh to use the new example/agent_tests.hcl

[robloxrob]

@lisongmin Awesome work on this PR! Added a few feedback items. Thank you so much for your efforts and contribution.

[shishir-a412ed]

LGTM