Managing etc files with chezmoi using hooks

[dgudim]

For some time, I have been managing some of my etc files with chezmoi. (Yeah, ik, this is not the intended usecase, but it works nicely)

How? Simple, it it's possible because of the new hooks! (pre-apply, post-update, etc)

All you need is this:

Post-update/apply hook

#!/usr/bin/python
import os
import sys
import glob

RED = "\033[0;31m"
L_PURPLE = "\033[1;35m"
NC = "\033[0m"
L_GREEN = "\033[1;32m"
YELLOW = "\033[0;33m"
L_YELLOW = "\033[1;33m"
L_CYAN = "\033[1;36m"
L_BLUE = "\033[1;34m"
BLUE = "\033[0;34m"
CYAN = "\033[0;36m"
GREEN = "\033[0;32m"


def getenv(name: str) -> str:
    val = os.getenv(name)
    if not val:
        print(f"{RED}{name} is unset!!{NC}")
        sys.exit(1)
    return val


print(
    f"{L_PURPLE}Running {L_BLUE}etc post update/apply hook{NC},{L_PURPLE} copying etc mirror to {L_CYAN}/etc{NC}..."
)

home = getenv("HOME")
real_etc_path = "/etc"
local_mirror_etc_path = os.path.join(home, ".config/etc_mirror")

entries = 0

for mirror_filepath in glob.iglob(
    local_mirror_etc_path + "**/**", recursive=True, dir_fd=False
):
    if not os.path.isfile(mirror_filepath):
        continue
    rel_path = mirror_filepath.replace(f"{local_mirror_etc_path}/", "")
    target_etc_file = os.path.join("/etc", rel_path)

    try:
        os.system(f"sudo mkdir -p {os.path.dirname(target_etc_file)}")
        os.system(
            f'sudo install --owner=root --group=root --mode=0644 "{mirror_filepath}" "{target_etc_file}"'
        )
        entries = entries + 1
    except Exception as e:
        print(
            f"{GREEN}Installing{NC} {BLUE}{mirror_filepath.replace(home, '~')}{NC} to {CYAN}{target_etc_file}{NC}",
            end="",
        )
        print(f"  {RED}ERR: {e}{NC}")

print(f"{L_GREEN}Finished copying to etc, {L_YELLOW}{entries} files {L_GREEN}processed{NC}")

Pre-update/apply hook

#!/usr/bin/python
import shutil
import os
import sys
import glob


RED = "\033[0;31m"
L_PURPLE = "\033[1;35m"
NC = "\033[0m"
L_GREEN = "\033[1;32m"
YELLOW = "\033[0;33m"
L_YELLOW = "\033[1;33m"
L_CYAN = "\033[1;36m"
L_BLUE = "\033[1;34m"
BLUE = "\033[0;34m"
CYAN = "\033[0;36m"
GREEN = "\033[0;32m"


def getenv(name: str) -> str:
    val = os.getenv(name)
    if not val:
        print(f"{RED}{name} is unset!!{NC}")
        sys.exit(1)
    return val


print(
    f"{L_PURPLE}Running {L_BLUE}etc pre update/apply hook{NC},{L_PURPLE} mirroring {L_CYAN}/etc{L_PURPLE} state{NC}..."
)

home = getenv("HOME")
real_etc_path = "/etc"
chezmoi_etc_path = os.path.join(
    getenv("CHEZMOI_SOURCE_DIR"), "dot_config/etc_mirror")
local_mirror_etc_path = os.path.join(home, ".config/etc_mirror")


def copyto(src: str, dst: str):
    dst = os.path.dirname(dst)
    try:
        os.makedirs(dst, exist_ok=True)
        os.system(f'cp -pf "{src}" "{dst}"')
        # print(f"  {L_GREEN}OK{NC}")
    except Exception as e:
        print(
            f"{GREEN}Copying{NC} {BLUE}{src}{NC} to {CYAN}{dst.replace(home, '~')}{NC}",
            end="",
        )
        print(f"  {RED}ERR: {e}{NC}")


entries = 0

for filepath in glob.iglob(chezmoi_etc_path + "**/**", recursive=True, dir_fd=False):
    if not os.path.isfile(filepath):
        continue
    rel_path = filepath.replace(
        f"{chezmoi_etc_path}/", "").replace(".tmpl", "")
    etc_file = os.path.join(real_etc_path, rel_path)
    local_mirror_file = os.path.join(local_mirror_etc_path, rel_path)
    copyto(etc_file, local_mirror_file)
    entries = entries + 1

print(f"{L_GREEN}Finished mirroring etc state{NC}, {L_YELLOW}{entries} files {L_GREEN}processed{NC}\n")

Pre-add hook

#!/usr/bin/python
import shutil
import os
import sys

RED = "\033[0;31m"
L_PURPLE = "\033[1;35m"
NC = "\033[0m"
L_GREEN = "\033[1;32m"
YELLOW = "\033[0;33m"
L_CYAN = "\033[1;36m"
L_BLUE = "\033[1;34m"
BLUE = "\033[0;34m"
CYAN = "\033[0;36m"
GREEN = "\033[0;32m"


def getenv(name: str) -> str:
    val = os.getenv(name)
    if not val:
        print(f"{name} is unset!!")
        sys.exit(1)
    return val


command_dir = getenv("CHEZMOI_COMMAND_DIR")
file_to_add = getenv("CHEZMOI_ARGS").split(" ").pop(-1)
source_path = os.path.join(command_dir, file_to_add)

if source_path.find("/etc") == -1:
    sys.exit(0)

if not os.path.exists(source_path):
    print(f"{RED}File does not exist!!{NC}")
    sys.exit(1)

st = oct(os.stat(source_path).st_mode & 0o777)[2:]

if st != "644":
    print(f"{RED}Wrong permissions (got {st}, expected 644)!!{NC}")
    sys.exit(0)

print(f"Detected a file in {L_CYAN}/etc{NC}, adding to chezmoi indirectly")
home = getenv("HOME")
chezmoi_etc_path = os.path.join(
    getenv("CHEZMOI_SOURCE_DIR"), "dot_config/etc_mirror")


def copyto(src: str, dst: str):
    print(
        f"{GREEN}Copying{NC} {BLUE}{src}{NC} to {CYAN}{dst.replace(home, '~')}{NC}",
        end="",
    )
    dst = os.path.dirname(dst)
    try:
        os.makedirs(dst, exist_ok=True)
        shutil.copy2(src, dst)
        print(f"  {L_GREEN}OK{NC}")
    except Exception as e:
        print(f"  {RED}ERR: {e}{NC}")


copyto(source_path, os.path.join(
    chezmoi_etc_path, source_path.replace("/etc/", "")))

How it works:

• Copies needed files (in dot_config/etc_mirror) from /etc to the .config/etc_mirror directory in home
• The regular chezmoi process runs with the template goodness and all of that, you also get prompted for differences
• Copies files from .config/etc_mirror modified by chezmoi back to /etc

Bonus!: With the pre-add hook, executing chezmoi add /etc/<some file> actually works!

kloud ❯❯ chezmoi add /etc/fuse.conf 
Detected a file in /etc, adding to chezmoi indirectly
Copying /etc/fuse.conf to ~/.local/share/chezmoi/dot_config/etc_mirror/fuse.conf  OK
chezmoi: /etc/fuse.conf: not in destination directory (/home/kloud)

Limitations: The permissions are not recorded anywhere, so the script only works for files with 644 permissions (which most of the files have anyway)

[halostatue]

Clever.