Recently I came across a problem where I need to share the host path to Nomad docker task. I have to say that the official document about this part does not explain very clear. I spent quite long time to find the solution.
Note that this is not about mounting the host volume to Nomad docker task. Just mount pure folder in host filesystem to Nomad docker task.
It is equivalent to the docker command like
docker run -d \
-it \
--name devtest \
-v "$(pwd)"/target:/app \
nginx:latest
The most important thing that the Nomad official document did not point out is that the Nomad agent configuration(.hcl) has to add docker plugin first. The below file is Nomad client agent configuration. See line 35-41.
1# Increase log verbosity
2log_level = "DEBUG"
3
4# Setup data dir
5data_dir = "/tmp/client1"
6
7# Enable the client
8client {
9 enabled = true
10
11 # For demo assume you are talking to server1. For production,
12 # this should be like "nomad.service.consul:4647" and a system
13 # like Consul used for service discovery.
14 servers = ["127.0.0.1:4647"]
15}
16
17# Modify our port to avoid a collision with server1
18ports {
19 http = 5656
20}
21
22# Require TLS
23tls {
24 http = true
25 rpc = true
26
27 ca_file = "nomad-ca.pem"
28 cert_file = "client.pem"
29 key_file = "client-key.pem"
30
31 verify_server_hostname = true
32 verify_https_client = true
33}
34
35plugin "docker" {
36 config {
37 volumes {
38 enabled = true
39 }
40 }
41}
After running Nomad client agent with the updated .hcl file. Next we need to update the job spec.
1# TARGET_PATH will be passed in by executing the "nomad job run -var TARGET_PATH=${pwd}/target xxx.hcl"
2variable TARGET_PATH {}
3
4job "nginx" {
5
6 datacenters = [var.DC]
7
8 group "nginx" {
9
10 task "nginx" {
11 driver = "docker"
12
13 config {
14 image = "nginx:latest"
15 force_pull = true
16
17 mount {
18 type = "bind"
19 target = "/app"
20 source = var.TARGET_PATH
21 readonly = false
22 bind_options {
23 propagation = "rshared"
24 }
25 }
26 }
27 }
28 }
29}
With the above configuration, the host path will be mount to Nomad docker task successfully.
You can find the official document about volume_mount.
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