我在EC2实例中运行某些服务时遇到了困难。我正在使用Amazon Linux AMI，并希望在我的实例首次启动时将neo4j（图形数据库）作为服务启动。
然而，我一直无法开始任何事情，更不用说neo4j了。我甚至无法获得亚马逊提供的基本tutorial user data script工作。我复制并粘贴了以下代码：
#!/bin/bash
yum update -y
yum install -y httpd24 php56 mysql55-server php56-mysqlnd
service httpd start
chkconfig httpd on
进入我的EC2实例的“用户数据”部分，然后启动我的EC2实例。从理论上讲，自httpd启动以来，我应该能够在浏览器中导航到我的实例的IP地址，并查看默认的Apache网页（我已允许端口80的入站HTTP进行安全组设置）。但是，我收到Connection refused错误。
在SSH进入我的实例后发出以下命令时，确认了这一点：
sudo su
service httpd status
响应是httpd is stopped，显然用户数据脚本应该启动它。亚马逊建议调试我检查/var/log/cloud-init-output.log是否有错误消息，但是在检查日志时我没有看到任何内容：
Cloud-init v. 0.7.6 running 'init-local' at Sun, 12 Nov 2017 16:41:03 +0000. Up 5.73 seconds.
Cloud-init v. 0.7.6 running 'init' at Sun, 12 Nov 2017 16:41:03 +0000. Up 5.91 seconds.
ci-info: +++++++++++++++++++++++Net device info+++++++++++++++++++++++
ci-info: Device Up Address Mask Hw-Address
ci-info: lo True 127.0.0.1 255.0.0.0 .
ci-info: eth0 True 172.31.7.27 255.255.240.0 0a:8c:a2:67:1f:46
ci-info: ++++++++++++++++++++++++++++++Route info+++++++++++++++++++++++++++++++
ci-info: Route Destination Gateway Genmask Interface Flags
ci-info: 0 0.0.0.0 172.31.0.1 0.0.0.0 eth0 UG
ci-info: 1 169.254.169.254 0.0.0.0 255.255.255.255 eth0 UH
ci-info: 2 172.31.0.0 0.0.0.0 255.255.240.0 eth0 U
Generating public/private rsa key pair.
Your identification has been saved in /etc/ssh/ssh_host_rsa_key.
Your public key has been saved in /etc/ssh/ssh_host_rsa_key.pub.
The key fingerprint is:
...
The key's randomart image is:
+---[RSA 2048]----+
[RANDOM ART]
+----[SHA256]-----+
Generating public/private dsa key pair.
Your identification has been saved in /etc/ssh/ssh_host_dsa_key.
Your public key has been saved in /etc/ssh/ssh_host_dsa_key.pub.
The key fingerprint is:
...
The key's randomart image is:
+---[DSA 1024]----+
+----[SHA256]-----+
Generating public/private ecdsa key pair.
Your identification has been saved in /etc/ssh/ssh_host_ecdsa_key.
Your public key has been saved in /etc/ssh/ssh_host_ecdsa_key.pub.
The key fingerprint is:
...
The key's randomart image is:
... [RANDOMART IMAGE]
Cloud-init v. 0.7.6 running 'modules:config' at Sun, 12 Nov 2017 16:41:04 +0000. Up 6.70 seconds.
Loaded plugins: priorities, update-motd, upgrade-helper
No packages needed for security; 0 packages available
No packages marked for update
Cloud-init v. 0.7.6 running 'modules:final' at Sun, 12 Nov 2017 16:41:08 +0000. Up 10.93 seconds.
Cloud-init v. 0.7.6 finished at Sun, 12 Nov 2017 16:41:08 +0000. Datasource DataSourceEc2. Up 11.04 seconds
Cloud-init v. 0.7.6 running 'init-local' at Sun, 12 Nov 2017 17:10:45 +0000. Up 5.85 seconds.
Cloud-init v. 0.7.6 running 'init' at Sun, 12 Nov 2017 17:10:46 +0000. Up 6.04 seconds.
ci-info: +++++++++++++++++++++++Net device info+++++++++++++++++++++++
ci-info: Device Up Address Mask Hw-Address
ci-info: lo True 127.0.0.1 255.0.0.0 .
ci-info: eth0 True 172.31.7.27 255.255.240.0 0a:8c:a2:67:1f:46
ci-info: ++++++++++++++++++++++++++++++Route info+++++++++++++++++++++++++++++++
ci-info: Route Destination Gateway Genmask Interface Flags
ci-info: 0 0.0.0.0 172.31.0.1 0.0.0.0 eth0 UG
ci-info: 1 169.254.169.254 0.0.0.0 255.255.255.255 eth0 UH
ci-info: 2 172.31.0.0 0.0.0.0 255.255.240.0 eth0 U
Cloud-init v. 0.7.6 running 'modules:config' at Sun, 12 Nov 2017 17:10:46 +0000. Up 6.61 seconds.
Cloud-init v. 0.7.6 running 'modules:final' at Sun, 12 Nov 2017 17:10:47 +0000. Up 7.03 seconds.
Cloud-init v. 0.7.6 finished at Sun, 12 Nov 2017 17:10:47 +0000. Datasource DataSourceEc2. Up 7.11 seconds
Cloud-init v. 0.7.6 running 'init-local' at Sun, 12 Nov 2017 17:18:25 +0000. Up 5.60 seconds.
Cloud-init v. 0.7.6 running 'init' at Sun, 12 Nov 2017 17:18:25 +0000. Up 5.79 seconds.
ci-info: +++++++++++++++++++++++Net device info+++++++++++++++++++++++
ci-info: Device Up Address Mask Hw-Address
ci-info: lo True 127.0.0.1 255.0.0.0 .
ci-info: eth0 True 172.31.7.27 255.255.240.0 0a:8c:a2:67:1f:46
ci-info: ++++++++++++++++++++++++++++++Route info+++++++++++++++++++++++++++++++
ci-info: Route Destination Gateway Genmask Interface Flags
ci-info: 0 0.0.0.0 172.31.0.1 0.0.0.0 eth0 UG
ci-info: 1 169.254.169.254 0.0.0.0 255.255.255.255 eth0 UH
ci-info: 2 172.31.0.0 0.0.0.0 255.255.240.0 eth0 U
Cloud-init v. 0.7.6 running 'modules:config' at Sun, 12 Nov 2017 17:18:26 +0000. Up 6.41 seconds.
Cloud-init v. 0.7.6 running 'modules:final' at Sun, 12 Nov 2017 17:18:26 +0000. Up 6.84 seconds.
Cloud-init v. 0.7.6 finished at Sun, 12 Nov 2017 17:18:26 +0000. Datasource DataSourceEc2. Up 6.93 seconds
我查看了StackOverflow上的类似帖子，发现了这个：user data script doesn't launch with ec2 instance。接受的答案是用户数据脚本只在第一个引导周期执行 - 这是否意味着我需要终止我的实例并启动一个全新的实例才能执行我的脚本？在这种情况下，我觉得这首先打破了启动脚本的整个目的！
编辑：我在一些echo测试语句中添加了以查看它们是否在日志中打印出来了！
但是，我确实从我的EC2实例中尝试curl http://169.254.169.254/latest/meta-data，并取回了这个输出：
#!/bin/bash
echo "Testing 1"
yum update -y
echo "Testing 2"
yum install -y httpd24 php56 mysql55-server php56-mysqlnd
echo "Testing 3"
service httpd start
chkconfig httpd on
所以它肯定会加载我的用户数据......只是不执行它。
答案 0 :(得分：1)
来自Configuring Instances with User Data
指定用户数据时，请注意以下事项：
- 用户数据被视为不透明数据：您所提供的就是您所获得的 背部。由实例决定是否能够解释它。
- 用户数据 限制为16 KB。此限制适用于原始形式的数据，而不适用 base64编码的形式。
- 用户数据必须是base64编码的。亚马逊EC2 console可以为您执行base64编码或接受 base64编码的输入。
- 检索用户数据时必须对其进行解码。 使用实例元数据检索数据时会解码数据 控制台。
- 用户数据仅在启动时执行。如果你停止了 实例，修改用户数据，并启动实例，即新用户 数据不会自动执行
Userdata仅在实例启动时运行。其目的是运行一次，以便在实例投入使用之前允许一次性服务器配置任务。
您是否希望每次重启时都运行软件安装过程？如果要在每次重新启动时启动进程，请查看/etc/rc.local。