336 lines
12 KiB
Go
336 lines
12 KiB
Go
package driver
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import (
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"encoding/json"
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"fmt"
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"log"
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"os/exec"
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"regexp"
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"strconv"
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"strings"
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docker "github.com/fsouza/go-dockerclient"
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"github.com/hashicorp/nomad/client/config"
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"github.com/hashicorp/nomad/nomad/structs"
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)
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var (
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reDockerVersion = regexp.MustCompile("Docker version ([\\d\\.]+),.+")
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reDockerSha = regexp.MustCompile("^[a-f0-9]{64}$")
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reNumeric = regexp.MustCompile("^[0-9]+$")
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)
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type DockerDriver struct {
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DriverContext
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}
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type dockerPID struct {
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ImageID string
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ContainerID string
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}
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type dockerHandle struct {
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logger *log.Logger
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imageID string
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containerID string
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waitCh chan error
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doneCh chan struct{}
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}
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func NewDockerDriver(ctx *DriverContext) Driver {
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return &DockerDriver{*ctx}
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}
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func (d *DockerDriver) Fingerprint(cfg *config.Config, node *structs.Node) (bool, error) {
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outBytes, err := exec.Command("docker", "-v").Output()
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out := strings.TrimSpace(string(outBytes))
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if err != nil {
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return false, nil
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}
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matches := reDockerVersion.FindStringSubmatch(out)
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if len(matches) != 2 {
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return false, fmt.Errorf("Unable to parse docker version string: %#v", matches)
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}
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node.Attributes["driver.docker"] = "true"
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node.Attributes["driver.docker.version"] = matches[1]
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return true, nil
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}
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// createContainer initializes a struct needed to call docker.client.CreateContainer()
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func createContainer(ctx *ExecContext, task *structs.Task, logger *log.Logger) docker.CreateContainerOptions {
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if task.Resources == nil {
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panic("task.Resources is nil and we can't constrain resource usage. We shouldn't have been able to schedule this in the first place.")
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}
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// hostConfig holds options for the docker container that are unique to this
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// machine, such as resource limits and port mappings
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hostConfig := &docker.HostConfig{
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// Convert MB to bytes. This is an absolute value.
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//
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// This value represents the total amount of memory a process can use.
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// Swap is added to total memory and is managed by the OS, not docker.
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// Since this may cause other processes to swap and cause system
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// instability, we will simply not use swap.
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//
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// See: https://www.kernel.org/doc/Documentation/cgroups/memory.txt
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Memory: int64(task.Resources.MemoryMB) * 1024 * 1024,
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MemorySwap: -1,
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// Convert Mhz to shares. This is a relative value.
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//
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// There are two types of CPU limiters available: Shares and Quotas. A
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// Share allows a particular process to have a proportion of CPU time
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// relative to other processes; 1024 by default. A CPU Quota is enforced
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// over a Period of time and is a HARD limit on the amount of CPU time a
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// process can use. Processes with quotas cannot burst, while processes
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// with shares can, so we'll use shares.
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//
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// The simplest scale is 1 share to 1 MHz so 1024 = 1GHz. This means any
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// given process will have at least that amount of resources, but likely
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// more since it is (probably) rare that the machine will run at 100%
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// CPU. This scale will cease to work if a node is overprovisioned.
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//
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// See:
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// - https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt
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// - https://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt
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CPUShares: int64(task.Resources.CPU),
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}
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logger.Printf("[DEBUG] driver.docker: using %d bytes memory for %s", hostConfig.Memory, task.Config["image"])
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logger.Printf("[DEBUG] driver.docker: using %d cpu shares for %s", hostConfig.CPUShares, task.Config["image"])
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// Setup port mapping (equivalent to -p on docker CLI). Ports must already be
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// exposed in the container.
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if len(task.Resources.Networks) == 0 {
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logger.Print("[WARN] driver.docker: No networks are available for port mapping")
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} else {
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network := task.Resources.Networks[0]
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dockerPorts := map[docker.Port][]docker.PortBinding{}
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for _, port := range network.ListStaticPorts() {
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dockerPorts[docker.Port(strconv.Itoa(port)+"/tcp")] = []docker.PortBinding{docker.PortBinding{HostIP: network.IP, HostPort: strconv.Itoa(port)}}
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dockerPorts[docker.Port(strconv.Itoa(port)+"/udp")] = []docker.PortBinding{docker.PortBinding{HostIP: network.IP, HostPort: strconv.Itoa(port)}}
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logger.Printf("[DEBUG] driver.docker: allocated port %s:%d -> %d (static) %s\n", network.IP, port, port)
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}
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for label, port := range network.MapDynamicPorts() {
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// If the label is numeric we expect that there is a service
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// listening on that port inside the container. In this case we'll
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// setup a mapping from our random host port to the label port.
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//
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// Otherwise we'll setup a direct 1:1 mapping from the host port to
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// the container, and assume that the process inside will read the
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// environment variable and bind to the correct port.
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if reNumeric.MatchString(label) {
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dockerPorts[docker.Port(label+"/tcp")] = []docker.PortBinding{docker.PortBinding{HostIP: network.IP, HostPort: strconv.Itoa(port)}}
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dockerPorts[docker.Port(label+"/udp")] = []docker.PortBinding{docker.PortBinding{HostIP: network.IP, HostPort: strconv.Itoa(port)}}
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logger.Printf("[DEBUG] driver.docker: allocated port %s:%d -> %s (mapped)", network.IP, port, label)
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} else {
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dockerPorts[docker.Port(strconv.Itoa(port)+"/tcp")] = []docker.PortBinding{docker.PortBinding{HostIP: network.IP, HostPort: strconv.Itoa(port)}}
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dockerPorts[docker.Port(strconv.Itoa(port)+"/udp")] = []docker.PortBinding{docker.PortBinding{HostIP: network.IP, HostPort: strconv.Itoa(port)}}
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logger.Printf("[DEBUG] driver.docker: allocated port %s:%d -> %d for label %s\n", network.IP, port, port, label)
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}
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}
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hostConfig.PortBindings = dockerPorts
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}
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return docker.CreateContainerOptions{
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Config: &docker.Config{
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Env: PopulateEnvironment(ctx, task),
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Image: task.Config["image"],
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},
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HostConfig: hostConfig,
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}
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}
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func (d *DockerDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle, error) {
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// Get the image from config
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image, ok := task.Config["image"]
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if !ok || image == "" {
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return nil, fmt.Errorf("Image not specified")
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}
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if task.Resources == nil {
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return nil, fmt.Errorf("Resources are not specified")
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}
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if task.Resources.MemoryMB == 0 {
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return nil, fmt.Errorf("Memory limit cannot be zero")
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}
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if task.Resources.CPU == 0 {
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return nil, fmt.Errorf("CPU limit cannot be zero")
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}
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// Initialize docker API client
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dockerEndpoint := d.config.ReadDefault("docker.endpoint", "unix:///var/run/docker.sock")
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client, err := docker.NewClient(dockerEndpoint)
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if err != nil {
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return nil, fmt.Errorf("Failed to connect to docker.endpoint (%s): %s", dockerEndpoint, err)
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}
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// Download the image
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pull, err := exec.Command("docker", "pull", image).CombinedOutput()
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if err != nil {
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d.logger.Printf("[ERR] driver.docker: pulling container %s", pull)
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return nil, fmt.Errorf("Failed to pull `%s`: %s", image, err)
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}
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d.logger.Printf("[DEBUG] driver.docker: docker pull %s:\n%s", image, pull)
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// Get the image ID (sha256). We need to keep track of this in case another
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// process pulls down a newer version of the image.
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imageIDBytes, err := exec.Command("docker", "images", "-q", "--no-trunc", image).CombinedOutput()
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// imageID := strings.TrimSpace(string(imageIDBytes))
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// TODO this is a hack and needs to get fixed :(
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imageID := strings.Split(strings.TrimSpace(string(imageIDBytes)), "\n")[0]
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if err != nil || imageID == "" {
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d.logger.Printf("[ERR] driver.docker: getting image id %s", imageID)
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return nil, fmt.Errorf("Failed to determine image id for `%s`: %s", image, err)
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}
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if !reDockerSha.MatchString(imageID) {
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return nil, fmt.Errorf("Image id not in expected format (sha256); found %s", imageID)
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}
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d.logger.Printf("[DEBUG] driver.docker: using image %s", imageID)
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d.logger.Printf("[INFO] driver.docker: downloaded image %s as %s", image, imageID)
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// Create a container
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container, err := client.CreateContainer(createContainer(ctx, task, d.logger))
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if err != nil {
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d.logger.Printf("[ERR] driver.docker: %s", err)
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return nil, fmt.Errorf("Failed to create container from image %s", image)
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}
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if !reDockerSha.MatchString(container.ID) {
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return nil, fmt.Errorf("Container id not in expected format (sha256); found %s", container.ID)
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}
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d.logger.Printf("[INFO] driver.docker: created container %s", container.ID)
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// Start the container
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startBytes, err := exec.Command("docker", "start", container.ID).CombinedOutput()
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if err != nil {
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d.logger.Printf("[ERR] driver.docker: starting container %s", strings.TrimSpace(string(startBytes)))
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return nil, fmt.Errorf("Failed to start container %s", container.ID)
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}
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d.logger.Printf("[INFO] driver.docker: started container %s", container.ID)
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// Return a driver handle
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h := &dockerHandle{
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logger: d.logger,
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imageID: imageID,
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containerID: container.ID,
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doneCh: make(chan struct{}),
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waitCh: make(chan error, 1),
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}
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go h.run()
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return h, nil
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}
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func (d *DockerDriver) Open(ctx *ExecContext, handleID string) (DriverHandle, error) {
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// Split the handle
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pidBytes := []byte(strings.TrimPrefix(handleID, "DOCKER:"))
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pid := &dockerPID{}
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err := json.Unmarshal(pidBytes, pid)
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if err != nil {
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return nil, fmt.Errorf("Failed to parse handle '%s': %v", handleID, err)
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}
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d.logger.Printf("[INFO] driver.docker: re-attaching to docker process: %s", handleID)
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// Look for a running container with this ID
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// docker ps does not return an exit code if there are no matching processes
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// so we have to read the output and compare it to our known containerID
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psBytes, err := exec.Command("docker", "ps", "-q", "--no-trunc",
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fmt.Sprintf("-f=id=%s", pid.ContainerID)).Output()
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ps := strings.TrimSpace(string(psBytes))
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if err != nil {
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return nil, fmt.Errorf("Failed to find container %s: %v", pid.ContainerID, err)
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} else if ps != pid.ContainerID {
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return nil, fmt.Errorf("Container ID does not match; expected %s found %s", pid.ContainerID, ps)
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}
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// Return a driver handle
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h := &dockerHandle{
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logger: d.logger,
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imageID: pid.ImageID,
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containerID: pid.ContainerID,
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doneCh: make(chan struct{}),
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waitCh: make(chan error, 1),
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}
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go h.run()
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return h, nil
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}
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func (h *dockerHandle) ID() string {
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// Return a handle to the PID
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pid := dockerPID{
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ImageID: h.imageID,
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ContainerID: h.containerID,
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}
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data, err := json.Marshal(pid)
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if err != nil {
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h.logger.Printf("[ERR] driver.docker: failed to marshal docker PID to JSON: %s", err)
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}
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return fmt.Sprintf("DOCKER:%s", string(data))
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}
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func (h *dockerHandle) WaitCh() chan error {
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return h.waitCh
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}
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func (h *dockerHandle) Update(task *structs.Task) error {
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// Update is not possible
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return nil
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}
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// Kill is used to terminate the task. This uses docker stop -t 5
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func (h *dockerHandle) Kill() error {
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// Stop the container
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stop, err := exec.Command("docker", "stop", "-t", "5", h.containerID).CombinedOutput()
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if err != nil {
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log.Printf("[ERR] driver.docker: stopping container %s", stop)
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return fmt.Errorf("Failed to stop container %s: %s", h.containerID, err)
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}
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log.Printf("[INFO] driver.docker: stopped container %s", h.containerID)
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// Cleanup container
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rmContainer, err := exec.Command("docker", "rm", h.containerID).CombinedOutput()
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if err != nil {
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log.Printf("[ERR] driver.docker: removing container %s", rmContainer)
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return fmt.Errorf("Failed to remove container %s: %s", h.containerID, err)
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}
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log.Printf("[INFO] driver.docker: removed container %s", h.containerID)
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// Cleanup image. This operation may fail if the image is in use by another
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// job. That is OK. Will we log a message but continue.
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_, err = exec.Command("docker", "rmi", h.imageID).CombinedOutput()
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if err != nil {
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log.Printf("[WARN] driver.docker: failed to remove image %s; it may still be in use", h.imageID)
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} else {
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log.Printf("[INFO] driver.docker: removed image %s", h.imageID)
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}
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return nil
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}
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func (h *dockerHandle) run() {
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// Wait for it...
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waitBytes, err := exec.Command("docker", "wait", h.containerID).Output()
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if err != nil {
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h.logger.Printf("[ERR] driver.docker: unable to wait for %s; container already terminated", h.containerID)
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}
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wait := strings.TrimSpace(string(waitBytes))
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// If the container failed, try to get the last 10 lines of logs for our
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// error message.
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if wait != "0" {
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var logsBytes []byte
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logsBytes, err = exec.Command("docker", "logs", "--tail=10", h.containerID).Output()
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logs := string(logsBytes)
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if err == nil {
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err = fmt.Errorf("%s", logs)
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}
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}
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close(h.doneCh)
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if err != nil {
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h.waitCh <- err
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}
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close(h.waitCh)
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}
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