cli/container: use github.com/moby/sys/capability for completions

We used a hard-coded list of capabilities that we copied from containerd,
but the new "capability" package allows use to have a maintained list
of capabilities.

There's likely still some improvements to be made;

First of all, the capability package could provide a function to get the list
of strings.

On the completion-side, we need to consider what format is most convenient;
currently we use the canonical name (uppercase and "CAP_" prefix), however,
tab-completion is case-sensitive by default, so requires the user to type
uppercase letters to filter the list of options.

Bash completion provides a `completion-ignore-case on` option to make completion
case-insensitive (https://askubuntu.com/a/87066), but it looks to be a global
option; the current cobra.CompletionOptions also don't provide this as an option
to be used in the generated completion-script.

Fish completion has `smartcase` (by default?) which matches any case if
all of the input is lowercase.

Zsh does not have a dedicated option, but allows setting matching-rules
(see https://superuser.com/a/1092328).

Signed-off-by: Sebastiaan van Stijn <[email protected]>

cli/command/container/completion.go

@@ -1,70 +1,48 @@
 package container
 
 import (
+	"strings"
+	"sync"
+
 	"github.com/docker/cli/cli/command/completion"
 	"github.com/docker/docker/api/types/container"
+	"github.com/moby/sys/capability"
 	"github.com/moby/sys/signal"
 	"github.com/spf13/cobra"
 )
 
+// allCaps is the magic value for "all capabilities".
+const allCaps = "ALL"
+
 // allLinuxCapabilities is a list of all known Linux capabilities.
 //
-// This list was based on the containerd pkg/cap package;
-// https://github.com/containerd/containerd/blob/v1.7.19/pkg/cap/cap_linux.go#L133-L181
-//
 // TODO(thaJeztah): add descriptions, and enable descriptions for our completion scripts (cobra.CompletionOptions.DisableDescriptions is currently set to "true")
-var allLinuxCapabilities = []string{
-	"ALL", // magic value for "all capabilities"
-
-	// caps35 is the caps of kernel 3.5 (37 entries)
-	"CAP_CHOWN",            // 2.2
-	"CAP_DAC_OVERRIDE",     // 2.2
-	"CAP_DAC_READ_SEARCH",  // 2.2
-	"CAP_FOWNER",           // 2.2
-	"CAP_FSETID",           // 2.2
-	"CAP_KILL",             // 2.2
-	"CAP_SETGID",           // 2.2
-	"CAP_SETUID",           // 2.2
-	"CAP_SETPCAP",          // 2.2
-	"CAP_LINUX_IMMUTABLE",  // 2.2
-	"CAP_NET_BIND_SERVICE", // 2.2
-	"CAP_NET_BROADCAST",    // 2.2
-	"CAP_NET_ADMIN",        // 2.2
-	"CAP_NET_RAW",          // 2.2
-	"CAP_IPC_LOCK",         // 2.2
-	"CAP_IPC_OWNER",        // 2.2
-	"CAP_SYS_MODULE",       // 2.2
-	"CAP_SYS_RAWIO",        // 2.2
-	"CAP_SYS_CHROOT",       // 2.2
-	"CAP_SYS_PTRACE",       // 2.2
-	"CAP_SYS_PACCT",        // 2.2
-	"CAP_SYS_ADMIN",        // 2.2
-	"CAP_SYS_BOOT",         // 2.2
-	"CAP_SYS_NICE",         // 2.2
-	"CAP_SYS_RESOURCE",     // 2.2
-	"CAP_SYS_TIME",         // 2.2
-	"CAP_SYS_TTY_CONFIG",   // 2.2
-	"CAP_MKNOD",            // 2.4
-	"CAP_LEASE",            // 2.4
-	"CAP_AUDIT_WRITE",      // 2.6.11
-	"CAP_AUDIT_CONTROL",    // 2.6.11
-	"CAP_SETFCAP",          // 2.6.24
-	"CAP_MAC_OVERRIDE",     // 2.6.25
-	"CAP_MAC_ADMIN",        // 2.6.25
-	"CAP_SYSLOG",           // 2.6.37
-	"CAP_WAKE_ALARM",       // 3.0
-	"CAP_BLOCK_SUSPEND",    // 3.5
-
-	// caps316 is the caps of kernel 3.16 (38 entries)
-	"CAP_AUDIT_READ",
-
-	// caps58 is the caps of kernel 5.8 (40 entries)
-	"CAP_PERFMON",
-	"CAP_BPF",
-
-	// caps59 is the caps of kernel 5.9 (41 entries)
-	"CAP_CHECKPOINT_RESTORE",
-}
+// TODO(thaJeztah): consider what casing we want to use for completion (see below);
+//
+// We need to consider what format is most convenient; currently we use the
+// canonical name (uppercase and "CAP_" prefix), however, tab-completion is
+// case-sensitive by default, so requires the user to type uppercase letters
+// to filter the list of options.
+//
+// Bash completion provides a `completion-ignore-case on` option to make completion
+// case-insensitive (https://askubuntu.com/a/87066), but it looks to be a global
+// option; the current cobra.CompletionOptions also don't provide this as an option
+// to be used in the generated completion-script.
+//
+// Fish completion has `smartcase` (by default?) which matches any case if
+// all of the input is lowercase.
+//
+// Zsh does not appear have a dedicated option, but allows setting matching-rules
+// (see https://superuser.com/a/1092328).
+var allLinuxCapabilities = sync.OnceValue(func() []string {
+	caps := capability.ListKnown()
+	out := make([]string, 0, len(caps)+1)
+	out = append(out, allCaps)
+	for _, c := range caps {
+		out = append(out, "CAP_"+strings.ToUpper(c.String()))
+	}
+	return out
+})
 
 // restartPolicies is a list of all valid restart-policies..
 //
@@ -77,7 +55,7 @@ var restartPolicies = []string{
 }
 
 func completeLinuxCapabilityNames(cmd *cobra.Command, args []string, toComplete string) (names []string, _ cobra.ShellCompDirective) {
-	return completion.FromList(allLinuxCapabilities...)(cmd, args, toComplete)
+	return completion.FromList(allLinuxCapabilities()...)(cmd, args, toComplete)
 }
 
 func completeRestartPolicies(cmd *cobra.Command, args []string, toComplete string) (names []string, _ cobra.ShellCompDirective) {

cli/command/container/completion_test.go

@@ -0,0 +1,21 @@
+package container
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/spf13/cobra"
+	"gotest.tools/v3/assert"
+	is "gotest.tools/v3/assert/cmp"
+)
+
+func TestCompleteLinuxCapabilityNames(t *testing.T) {
+	names, directives := completeLinuxCapabilityNames(nil, nil, "")
+	assert.Check(t, is.Equal(directives&cobra.ShellCompDirectiveNoFileComp, cobra.ShellCompDirectiveNoFileComp), "Should not perform file completion")
+	assert.Assert(t, len(names) > 1)
+	assert.Check(t, names[0] == allCaps)
+	for _, name := range names[1:] {
+		assert.Check(t, strings.HasPrefix(name, "CAP_"))
+		assert.Check(t, is.Equal(name, strings.ToUpper(name)), "Should be formatted uppercase")
+	}
+}

vendor.mod

@@ -26,6 +26,7 @@ require (
 	github.com/mattn/go-runewidth v0.0.15
 	github.com/moby/patternmatcher v0.6.0
 	github.com/moby/swarmkit/v2 v2.0.0-20240611172349-ea1a7cec35cb
+	github.com/moby/sys/capability v0.3.0
 	github.com/moby/sys/sequential v0.6.0
 	github.com/moby/sys/signal v0.7.1
 	github.com/moby/term v0.5.0

vendor.sum

@@ -182,6 +182,8 @@ github.com/moby/patternmatcher v0.6.0 h1:GmP9lR19aU5GqSSFko+5pRqHi+Ohk1O69aFiKkV
 github.com/moby/patternmatcher v0.6.0/go.mod h1:hDPoyOpDY7OrrMDLaYoY3hf52gNCR/YOUYxkhApJIxc=
 github.com/moby/swarmkit/v2 v2.0.0-20240611172349-ea1a7cec35cb h1:1UTTg2EgO3nuyV03wREDzldqqePzQ4+0a5G1C1y1bIo=
 github.com/moby/swarmkit/v2 v2.0.0-20240611172349-ea1a7cec35cb/go.mod h1:kNy225f/gWAnF8wPftteMc5nbAHhrH+HUfvyjmhFjeQ=
+github.com/moby/sys/capability v0.3.0 h1:kEP+y6te0gEXIaeQhIi0s7vKs/w0RPoH1qPa6jROcVg=
+github.com/moby/sys/capability v0.3.0/go.mod h1:4g9IK291rVkms3LKCDOoYlnV8xKwoDTpIrNEE35Wq0I=
 github.com/moby/sys/sequential v0.6.0 h1:qrx7XFUd/5DxtqcoH1h438hF5TmOvzC/lspjy7zgvCU=
 github.com/moby/sys/sequential v0.6.0/go.mod h1:uyv8EUTrca5PnDsdMGXhZe6CCe8U/UiTWd+lL+7b/Ko=
 github.com/moby/sys/signal v0.7.1 h1:PrQxdvxcGijdo6UXXo/lU/TvHUWyPhj7UOpSo8tuvk0=