podman

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package config
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import (
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	"fmt"
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	"os"
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	"strings"
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	"github.com/containers/buildah/docker"
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	"github.com/containers/image/v5/manifest"
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	v1 "github.com/opencontainers/image-spec/specs-go/v1"
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	"github.com/openshift/imagebuilder"
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)
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// firstStringElseSecondString takes two strings, and returns the first
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// string if it isn't empty, else the second string
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func firstStringElseSecondString(first, second string) string {
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	if first != "" {
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		return first
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	}
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	return second
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}
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// firstSliceElseSecondSlice takes two string slices, and returns the first
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// slice of strings if it has contents, else the second slice
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func firstSliceElseSecondSlice(first, second []string) []string {
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	if len(first) > 0 {
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		return append([]string{}, first...)
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	}
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	return append([]string{}, second...)
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}
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// firstSlicePairElseSecondSlicePair takes two pairs of string slices, and
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// returns the first pair of slices if either has contents, else the second
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// pair
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func firstSlicePairElseSecondSlicePair(firstA, firstB, secondA, secondB []string) ([]string, []string) {
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	if len(firstA) > 0 || len(firstB) > 0 {
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		return append([]string{}, firstA...), append([]string{}, firstB...)
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	}
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	return append([]string{}, secondA...), append([]string{}, secondB...)
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}
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// mergeEnv combines variables from a and b into a single environment slice. if
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// a and b both provide values for the same variable, the value from b is
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// preferred
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func mergeEnv(a, b []string) []string {
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	index := make(map[string]int)
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	results := make([]string, 0, len(a)+len(b))
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	for _, kv := range append(append([]string{}, a...), b...) {
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		k, _, specifiesValue := strings.Cut(kv, "=")
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		if !specifiesValue {
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			if value, ok := os.LookupEnv(kv); ok {
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				kv = kv + "=" + value
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			} else {
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				kv = kv + "="
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			}
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		}
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		if i, seen := index[k]; seen {
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			results[i] = kv
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		} else {
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			index[k] = len(results)
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			results = append(results, kv)
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		}
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	}
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	return results
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}
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// Override takes a buildah docker config and an OCI ImageConfig, and applies a
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// mixture of a slice of Dockerfile-style instructions and fields from a config
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// blob to them both
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func Override(dconfig *docker.Config, oconfig *v1.ImageConfig, overrideChanges []string, overrideConfig *manifest.Schema2Config) error {
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	if len(overrideChanges) > 0 {
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		if overrideConfig == nil {
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			overrideConfig = &manifest.Schema2Config{}
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		}
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		// Parse the set of changes as we would a Dockerfile.
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		changes := strings.Join(overrideChanges, "\n")
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		parsed, err := imagebuilder.ParseDockerfile(strings.NewReader(changes))
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		if err != nil {
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			return fmt.Errorf("parsing change set %+v: %w", changes, err)
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		}
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		// Create a dummy builder object to process configuration-related
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		// instructions.
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		subBuilder := imagebuilder.NewBuilder(nil)
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		// Convert the incoming data into an initial RunConfig.
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		subBuilder.RunConfig = *GoDockerclientConfigFromSchema2Config(overrideConfig)
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		// Process the change instructions one by one.
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		for _, node := range parsed.Children {
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			var step imagebuilder.Step
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			if err := step.Resolve(node); err != nil {
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				return fmt.Errorf("resolving change %q: %w", node.Original, err)
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			}
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			if err := subBuilder.Run(&step, &configOnlyExecutor{}, true); err != nil {
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				return fmt.Errorf("processing change %q: %w", node.Original, err)
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			}
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		}
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		// Pull settings out of the dummy builder's RunConfig.
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		overrideConfig = Schema2ConfigFromGoDockerclientConfig(&subBuilder.RunConfig)
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	}
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	if overrideConfig != nil {
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		// Apply changes from a possibly-provided possibly-changed config struct.
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		dconfig.Hostname = firstStringElseSecondString(overrideConfig.Hostname, dconfig.Hostname)
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		dconfig.Domainname = firstStringElseSecondString(overrideConfig.Domainname, dconfig.Domainname)
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		dconfig.User = firstStringElseSecondString(overrideConfig.User, dconfig.User)
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		oconfig.User = firstStringElseSecondString(overrideConfig.User, oconfig.User)
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		dconfig.AttachStdin = overrideConfig.AttachStdin
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		dconfig.AttachStdout = overrideConfig.AttachStdout
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		dconfig.AttachStderr = overrideConfig.AttachStderr
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		if len(overrideConfig.ExposedPorts) > 0 {
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			dexposedPorts := make(map[docker.Port]struct{})
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			oexposedPorts := make(map[string]struct{})
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			for port := range dconfig.ExposedPorts {
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				dexposedPorts[port] = struct{}{}
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			}
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			for port := range overrideConfig.ExposedPorts {
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				dexposedPorts[docker.Port(port)] = struct{}{}
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			}
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			for port := range oconfig.ExposedPorts {
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				oexposedPorts[port] = struct{}{}
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			}
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			for port := range overrideConfig.ExposedPorts {
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				oexposedPorts[string(port)] = struct{}{}
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			}
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			dconfig.ExposedPorts = dexposedPorts
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			oconfig.ExposedPorts = oexposedPorts
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		}
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		dconfig.Tty = overrideConfig.Tty
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		dconfig.OpenStdin = overrideConfig.OpenStdin
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		dconfig.StdinOnce = overrideConfig.StdinOnce
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		if len(overrideConfig.Env) > 0 {
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			dconfig.Env = mergeEnv(dconfig.Env, overrideConfig.Env)
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			oconfig.Env = mergeEnv(oconfig.Env, overrideConfig.Env)
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		}
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		dconfig.Entrypoint, dconfig.Cmd = firstSlicePairElseSecondSlicePair(overrideConfig.Entrypoint, overrideConfig.Cmd, dconfig.Entrypoint, dconfig.Cmd)
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		oconfig.Entrypoint, oconfig.Cmd = firstSlicePairElseSecondSlicePair(overrideConfig.Entrypoint, overrideConfig.Cmd, oconfig.Entrypoint, oconfig.Cmd)
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		if overrideConfig.Healthcheck != nil {
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			dconfig.Healthcheck = &docker.HealthConfig{
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				Test:        append([]string{}, overrideConfig.Healthcheck.Test...),
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				Interval:    overrideConfig.Healthcheck.Interval,
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				Timeout:     overrideConfig.Healthcheck.Timeout,
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				StartPeriod: overrideConfig.Healthcheck.StartPeriod,
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				Retries:     overrideConfig.Healthcheck.Retries,
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			}
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		}
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		dconfig.ArgsEscaped = overrideConfig.ArgsEscaped
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		dconfig.Image = firstStringElseSecondString(overrideConfig.Image, dconfig.Image)
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		if len(overrideConfig.Volumes) > 0 {
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			if dconfig.Volumes == nil {
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				dconfig.Volumes = make(map[string]struct{})
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			}
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			if oconfig.Volumes == nil {
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				oconfig.Volumes = make(map[string]struct{})
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			}
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			for volume := range overrideConfig.Volumes {
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				dconfig.Volumes[volume] = struct{}{}
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				oconfig.Volumes[volume] = struct{}{}
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			}
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		}
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		dconfig.WorkingDir = firstStringElseSecondString(overrideConfig.WorkingDir, dconfig.WorkingDir)
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		oconfig.WorkingDir = firstStringElseSecondString(overrideConfig.WorkingDir, oconfig.WorkingDir)
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		dconfig.NetworkDisabled = overrideConfig.NetworkDisabled
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		dconfig.MacAddress = overrideConfig.MacAddress
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		dconfig.OnBuild = overrideConfig.OnBuild
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		if len(overrideConfig.Labels) > 0 {
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			if dconfig.Labels == nil {
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				dconfig.Labels = make(map[string]string)
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			}
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			if oconfig.Labels == nil {
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				oconfig.Labels = make(map[string]string)
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			}
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			for k, v := range overrideConfig.Labels {
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				dconfig.Labels[k] = v
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				oconfig.Labels[k] = v
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			}
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		}
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		dconfig.StopSignal = overrideConfig.StopSignal
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		oconfig.StopSignal = overrideConfig.StopSignal
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		dconfig.StopTimeout = overrideConfig.StopTimeout
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		dconfig.Shell = firstSliceElseSecondSlice(overrideConfig.Shell, dconfig.Shell)
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	}
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	return nil
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}
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