普通用户启动supervisor报HTTP错误(strace)解决分析

目录

• 报错信息
• 关于 strace 命令

报错信息

公司得开发对生产环境都有普通用户 www 得权限，采用堡垒机登录到生产环境得机器。

默认 supervisor 使用 root 用户启动，开发没有权限直接修改配置和操作 supervisor 管理得进程，所以 supervisor 都采用 www 用户启动就解决问题了。

但是今天操作生产环境得时候，报得错误令人懵逼，SRE 同学折腾了好久，配置来配置去，搞不明白为啥 www 就是启动不了 supervisor ！

报错信息是这样得：

[www@**************** ~]$ supervisord -c /etc/supervisord.confError: Cannot open an HTTP server: socket.error reported errno.EACCES (13)For help, use /usr/bin/supervisord -h

翻遍谷歌、百度，找到得资料，没有一个真得能解决了问题，焦头烂额。

突然想起 strace 这个命令，于是乎，我改成这样子执行：

[www@**************** ~]$ strace supervisord -c /etc/supervisord.conf

奇迹发生了！

read(6, "S(1N(3R'R R24(1"..., 4096) = 1381read(6, "", 4096)                       = 0close(6)                                = 0close(5)                                = 0close(4)                                = 0getpid()                                = 3656unlink("/var/run/supervisor/supervisor.sock.3656") = -1 ENOENT (No such file or directory)socket(AF_UNIX, SOCK_STREAM, 0)         = 4bind(4, {sa_family=AF_UNIX, sun_path="/var/run/supervisor/supervisor.sock.3656"}, 42) = -1 EACCES (Permission denied)unlink("/var/run/supervisor/supervisor.sock.3656") = -1 ENOENT (No such file or directory)write(2, "Error: Cannot open an HTTP serve"..., 75Error: Cannot open an HTTP server: socket.error reported errno.EACCES (13)) = 75write(2, "For help, use /usr/bin/superviso"..., 38For help, use /usr/bin/supervisord -h) = 38close(4)                                = 0rt_sigaction(SIGINT, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa06ce997e0}, {sa_handler=0x7fa06d1b0750, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fa06ce997e0}, 8) = 0close(3)                                = 0close(11)                               = 0exit_group(2)                           = ?+++ exited with 2 +++

原来是没有权限，把 sock 文件挪到 www 用户下，问题解决。

关于 strace 命令

如果你得服务器还没安装 strace，可以用下面命令安装：

# Ubuntu / Debiansudo apt install strace# CentOSyum install -y strace

如果一个进程已经在运行，可以通过 PID 跟踪程序得系统调用，使用 CTRL + C 中止跟踪：

[root@**************** ~]# strace -p 16701strace: Process 16701 attachedrestart_syscall(<... resuming interrupted read ...>) = 0sendto(8, "*2rn$4rnLLENrn$52rnhorizon:comma"..., 73, MSG_DONTWAIT, NULL, 0) = 73poll([{fd=8, events=POLLIN|POLLERR|POLLHUP}], 1, 60000) = 1 ([{fd=8, revents=POLLIN}])recvfrom(8, ":0rn", 8192, MSG_DONTWAIT, NULL, NULL) = 4sendto(9, "*2rn$4rnLLENrn$14rnqueues:defaul"..., 35, MSG_DONTWAIT, NULL, 0) = 35poll([{fd=9, events=POLLIN|POLLERR|POLLHUP}], 1, 60000) = 1 ([{fd=9, revents=POLLIN}])recvfrom(9, ":0rn", 8192, MSG_DONTWAIT, NULL, NULL) = 4sendto(8, "*3rn$4rnHGETrn$21rnhorizon:queue"..., 55, MSG_DONTWAIT, NULL, 0) = 55poll([{fd=8, events=POLLIN|POLLERR|POLLHUP}], 1, 60000) = 1 ([{fd=8, revents=POLLIN}])recvfrom(8, "$18rn1.6690604487864007rn", 8192, MSG_DONTWAIT, NULL, NULL) = 25wait4(16711, 0x7ffeaafa566c, WNOHANG|WSTOPPED, NULL) = 0select(15, [12 14], [], [], {tv_sec=0, tv_usec=0}) = 0 (Timeout)wait4(16712, 0x7ffeaafa566c, WNOHANG|WSTOPPED, NULL) = 0select(17, [13 16], [], [], {tv_sec=0, tv_usec=0}) = 0 (Timeout)wait4(16713, 0x7ffeaafa566c, WNOHANG|WSTOPPED, NULL) = 0select(19, [15 18], [], [], {tv_sec=0, tv_usec=0}) = 0 (Timeout)sendto(8, "*14rn$5rnHMSETrn$54rnhorizon:sup"..., 500, MSG_DONTWAIT, NULL, 0) = 500sendto(8, "*4rn$4rnZADDrn$19rnhorizon:super"..., 99, MSG_DONTWAIT, NULL, 0) = 99sendto(8, "*3rn$6rnEXPIRErn$54rnhorizon:sup"..., 85, MSG_DONTWAIT, NULL, 0) = 85poll([{fd=8, events=POLLIN|POLLERR|POLLHUP}], 1, 60000) = 1 ([{fd=8, revents=POLLIN}])recvfrom(8, "+OKrn:0rn:1rn", 8192, MSG_DONTWAIT, NULL, NULL) = 13sendto(8, "*3rn$5rnSETNXrn$29rnhorizon:moni"..., 58, MSG_DONTWAIT, NULL, 0) = 58poll([{fd=8, events=POLLIN|POLLERR|POLLHUP}], 1, 60000) = 1 ([{fd=8, revents=POLLIN}])recvfrom(8, ":0rn", 8192, MSG_DONTWAIT, NULL, NULL) = 4rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0rt_sigaction(SIGCHLD, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0nanosleep({tv_sec=1, tv_nsec=0}, 0x7ffeaafa54a0) = 0sendto(8, "*2rn$4rnLLENrn$52rnhorizon:comma"..., 73, MSG_DONTWAIT, NULL, 0) = 73poll([{fd=8, events=POLLIN|POLLERR|POLLHUP}], 1, 60000) = 1 ([{fd=8, revents=POLLIN}])recvfrom(8, ":0rn", 8192, MSG_DONTWAIT, NULL, NULL) = 4wait4(16711, 0x7ffeaafa566c, WNOHANG|WSTOPPED, NULL) = 0select(15, [12 14], [], [], {tv_sec=0, tv_usec=0}) = 0 (Timeout)wait4(16712, 0x7ffeaafa566c, WNOHANG|WSTOPPED, NULL) = 0select(17, [13 16], [], [], {tv_sec=0, tv_usec=0}) = 0 (Timeout)wait4(16713, 0x7ffeaafa566c, WNOHANG|WSTOPPED, NULL) = 0select(19, [15 18], [], [], {tv_sec=0, tv_usec=0}) = 0 (Timeout)sendto(8, "*14rn$5rnHMSETrn$54rnhorizon:sup"..., 500, MSG_DONTWAIT, NULL, 0) = 500sendto(8, "*4rn$4rnZADDrn$19rnhorizon:super"..., 99, MSG_DONTWAIT, NULL, 0) = 99sendto(8, "*3rn$6rnEXPIRErn$54rnhorizon:sup"..., 85, MSG_DONTWAIT, NULL, 0) = 85poll([{fd=8, events=POLLIN|POLLERR|POLLHUP}], 1, 60000) = 1 ([{fd=8, revents=POLLIN}])recvfrom(8, "+OKrn:0rn:1rn", 8192, MSG_DONTWAIT, NULL, NULL) = 13sendto(8, "*3rn$5rnSETNXrn$29rnhorizon:moni"..., 58, MSG_DONTWAIT, NULL, 0) = 58poll([{fd=8, events=POLLIN|POLLERR|POLLHUP}], 1, 60000) = 1 ([{fd=8, revents=POLLIN}])recvfrom(8, ":0rn", 8192, MSG_DONTWAIT, NULL, NULL) = 4rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0rt_sigaction(SIGCHLD, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0nanosleep({tv_sec=1, tv_nsec=0}, ^Cstrace: Process 16701 detached <detached ...>

使用 -c 参数，可以得到各个系统调用得耗时、调用次数、错误数：

[root@**************** ~]# strace -p 16701 -cstrace: Process 16701 attached^Cstrace: Process 16701 detached% time     seconds  usecs/call     calls    errors syscall------ ----------- ----------- --------- --------- ---------------- 54.00    0.000216           5        39           sendto 11.25    0.000045           1        25           recvfrom  9.25    0.000037           1        25           poll  8.25    0.000033           5         6           nanosleep  6.50    0.000026           1        21           select  5.75    0.000023           1        21           wait4  3.50    0.000014           1        14           rt_sigprocmask  1.50    0.000006           0         7           rt_sigaction  0.00    0.000000           0         1           restart_syscall------ ----------- ----------- --------- --------- ----------------100.00    0.000400                   159           total

使用 -tt 参数，显示时间戳（微妙），-T 参数显示系统调用得耗时，合起来用效果是这样得：

[root@**************** ~]# strace -p 16701 -tt -Tstrace: Process 16701 attached23:05:15.019519 restart_syscall(<... resuming interrupted read ...>) = 0 <0.915045>23:05:15.934770 sendto(8, "*2rn$4rnLLENrn$52rnhorizon:comma"..., 73, MSG_DONTWAIT, NULL, 0) = 73 <0.000080>23:05:15.934975 poll([{fd=8, events=POLLIN|POLLERR|POLLHUP}], 1, 60000) = 1 ([{fd=8, revents=POLLIN}]) <0.000022>23:05:15.935065 recvfrom(8, ":0rn", 8192, MSG_DONTWAIT, NULL, NULL) = 4 <0.000022>23:05:15.935215 wait4(16711, 0x7ffeaafa566c, WNOHANG|WSTOPPED, NULL) = 0 <0.000023>23:05:15.935301 select(15, [12 14], [], [], {tv_sec=0, tv_usec=0}) = 0 (Timeout) <0.000026>23:05:15.935390 wait4(16712, 0x7ffeaafa566c, WNOHANG|WSTOPPED, NULL) = 0 <0.000018>23:05:15.935446 select(17, [13 16], [], [], {tv_sec=0, tv_usec=0}) = 0 (Timeout) <0.000018>23:05:15.935503 wait4(16713, 0x7ffeaafa566c, WNOHANG|WSTOPPED, NULL) = 0 <0.000023>23:05:15.935574 select(19, [15 18], [], [], {tv_sec=0, tv_usec=0}) = 0 (Timeout) <0.000023>23:05:15.935731 sendto(8, "*14rn$5rnHMSETrn$54rnhorizon:sup"..., 500, MSG_DONTWAIT, NULL, 0) = 500 <0.000059>23:05:15.935848 sendto(8, "*4rn$4rnZADDrn$19rnhorizon:super"..., 99, MSG_DONTWAIT, NULL, 0) = 99 <0.000046>23:05:15.935937 sendto(8, "*3rn$6rnEXPIRErn$54rnhorizon:sup"..., 85, MSG_DONTWAIT, NULL, 0) = 85 <0.000041>23:05:15.936028 poll([{fd=8, events=POLLIN|POLLERR|POLLHUP}], 1, 60000) = 1 ([{fd=8, revents=POLLIN}]) <0.000019>23:05:15.936088 recvfrom(8, "+OKrn:0rn:1rn", 8192, MSG_DONTWAIT, NULL, NULL) = 13 <0.000018>23:05:15.936278 sendto(8, "*3rn$5rnSETNXrn$29rnhorizon:moni"..., 58, MSG_DONTWAIT, NULL, 0) = 58 <0.000057>23:05:15.936385 poll([{fd=8, events=POLLIN|POLLERR|POLLHUP}], 1, 60000) = 1 ([{fd=8, revents=POLLIN}]) <0.000019>23:05:15.936441 recvfrom(8, ":0rn", 8192, MSG_DONTWAIT, NULL, NULL) = 4 <0.000017>23:05:15.936505 rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0 <0.000017>23:05:15.936564 rt_sigaction(SIGCHLD, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0 <0.000023>23:05:15.936624 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0 <0.000017>23:05:15.936672 nanosleep({tv_sec=1, tv_nsec=0}, ^Cstrace: Process 16701 detached <detached ...>

常用得参数也就这么几个，如果记不住，直接看帮助吧：）

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