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Improve agent resiliency

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Coder's agent can automatically lower the scheduling priority and raise the OOM (out-of-memory) kill score of user processes so the agent itself stays alive under resource pressure.

Prerequisites

Linux — The feature is ignored on other operating systems.
CAP_SYS_NICE is required if the agent needs to lower the nice value below its current value. In Kubernetes, add it to the container's security context:

container { security_context { capabilities { add = ["CAP_SYS_NICE"] } } }

Environment variables

Configure the feature with environment variables in the environment that launches the agent binary. These must be set on the workspace container or host, not in the coder_agent resource's env block. The agent reads them from its own process environment at startup.

Variable	Required	Default	Description
`CODER_PROC_PRIO_MGMT`	Yes	—	Set to enable the feature. The agent checks whether the variable is present, not its value — even an empty string enables it. Use `1` by convention. To disable, unset the variable entirely.
`CODER_PROC_OOM_SCORE`	No	Computed from agent's score	Explicit `oom_score_adj` value for child processes. Range: `-1000` to `1000`.
`CODER_PROC_NICE_SCORE`	No	Agent nice + 5 (capped at 19)	Explicit nice value for child processes. Range: `-20` to `19` (higher = lower priority).

OOM score defaults

If you do not set CODER_PROC_OOM_SCORE, the agent computes a value based on its own oom_score_adj:

Agent's `oom_score_adj`	Child score	Rationale
Negative (< 0)	`0`	Children are treated as normal processes.
>= 998	`1000`	Children get the maximum score (killed first).
Any other value	`998`	Children get a near-maximum score.

The goal is for the kernel's OOM killer to target child processes before the agent, keeping remote connectivity alive even when a workspace runs out of memory.

Nice score defaults

If you do not set CODER_PROC_NICE_SCORE, the agent sets children to its own nice value plus 5, capped at 19. This gives the agent more CPU scheduling priority than user workloads.

Example

The following Kubernetes template snippet enables process priority management on the workspace container:

resource "kubernetes_deployment" "workspace" {
  # ... other configuration

  spec {
    template {
      spec {
        container {
          name  = "dev"
          image = "codercom/example-base:ubuntu"

          env {
            name  = "CODER_AGENT_TOKEN"
            value = coder_agent.main.token
          }
          env {
            name  = "CODER_PROC_PRIO_MGMT"
            value = "1"
          }
          env {
            name  = "CODER_PROC_OOM_SCORE"
            value = "10"
          }
          env {
            name  = "CODER_PROC_NICE_SCORE"
            value = "1"
          }

          security_context {
            capabilities {
              add = ["CAP_SYS_NICE"]
            }
          }
        }
      }
    }
  }
}

CODER_PROC_OOM_SCORE=10 gives child processes a slightly elevated OOM score while keeping them well below the maximum.
CODER_PROC_NICE_SCORE=1 gives children a mildly lower CPU priority than the agent.
CAP_SYS_NICE allows the agent to set nice values.

Troubleshooting

OOM score adjustment fails

If you see failed to adjust oom score in stderr but the process still starts, the agent likely lacks permission to write to /proc/self/oom_score_adj. Ensure the process is dumpable (the agent handles this automatically, but it can fail if the container runtime restricts prctl calls).

Nice value is not applied

If you see failed to adjust niceness in stderr, nice values can only be increased (lowered in priority) without CAP_SYS_NICE. If your template sets a CODER_PROC_NICE_SCORE lower than the agent's current nice value, add the capability to the container's security context.

Environment variables leak to nested Coder agents

The agent strips all CODER_PROC_* variables from child environments automatically. This prevents interference in "Coder on Coder" development scenarios where a workspace runs another Coder agent.

Verify the feature is enabled

The agent logs whether process priority management is active at startup. Look for these lines in the agent log:

"process priority management enabled"
"process priority management not enabled (linux-only)"

The log entry includes the CODER_PROC_PRIO_MGMT value and the operating system. Check the agent log file at <log-dir>/coder-agent.log or stderr output.

Feature has no effect on macOS or Windows

Process priority management is Linux-only. Setting CODER_PROC_PRIO_MGMT on other operating systems is safe but has no effect.