What is the best way to change a field of a conf file in centos

Sam_Su · March 26, 2014, 12:23am

Hi,

I am trying to change a field (here is “net.ipv4.ip_nonlocal_bind=1”) of
the file /etc/sysctl.conf, currently I am using template to change the
field, however someone complained that it was not good to template the
system file '‘sysctl.conf’, because it may also used by other cookbooks. I
agreed with that guy, it is definitely better to only change a specific
field instead of the whole file with respect to a system file.

I am wondering what is the best way to change a specific field of a config
file in Chef.
It will be much appreciated if someone can give me some hints and share
some opinions.

Thanks,
Sam

Mike_Dillion · March 26, 2014, 12:37am

Sam,

Check out Chef::Util::FileEdit to match and replace lines in a single file
without replacing the entire file with a template. The chef-server cookbook
has a good example of this here:

github.com

chef-cookbooks/chef-server/blob/main/recipes/default.rb#L101


      
          #
          # Cookbook:: chef-server
          # Recipe:: default
          #
          # Copyright:: 2015-2019, Chef Software, Inc.
          #
          # Licensed under the Apache License, Version 2.0 (the "License");
          # you may not use this file except in compliance with the License.
          # You may obtain a copy of the License at
          #
          #     http://www.apache.org/licenses/LICENSE-2.0
          #
          # Unless required by applicable law or agreed to in writing, software
          # distributed under the License is distributed on an "AS IS" BASIS,
          # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
          # See the License for the specific language governing permissions and
          # limitations under the License.
          #
          
          cache_path = Chef::Config[:file_cache_path]
          
          ruby_block 'ensure node can resolve API FQDN' do
            extend ChefServerCookbook::Helpers
            block { repair_api_fqdn }
            only_if { api_fqdn_available? }
            not_if { api_fqdn_resolves? }
          end
          
          chef_ingredient 'chef-server' do
            extend ChefServerCookbook::Helpers
            version node['chef-server']['version'] unless node['chef-server']['version'].nil?
            package_source node['chef-server']['package_source']
            options node['chef-server']['options'] unless node['chef-server']['options'].nil?
            accept_license node['chef-server']['accept_license']
            config <<-EOS
          topology "#{node['chef-server']['topology']}"
          #{"api_fqdn \"#{node['chef-server']['api_fqdn']}\"" if api_fqdn_available?}
          #{node['chef-server']['configuration']}
            EOS
            action :install
          end
          
          file "#{cache_path}/chef-server-core.firstrun" do
            action :create
          end
          
          ingredient_config 'chef-server' do
            notifies :reconfigure, 'chef_ingredient[chef-server]', :immediately
          end

Cheers,
MikeD

On Tue, Mar 25, 2014 at 8:23 PM, Sam Su sam.debian@gmail.com wrote:

Hi,

I am trying to change a field (here is "net.ipv4.ip_nonlocal_bind=1") of
the file /etc/sysctl.conf, currently I am using template to change the
field, however someone complained that it was not good to template the
system file ''sysctl.conf', because it may also used by other cookbooks. I
agreed with that guy, it is definitely better to only change a specific
field instead of the whole file with respect to a system file.

I am wondering what is the best way to change a specific field of a config
file in Chef.
It will be much appreciated if someone can give me some hints and share
some opinions.

Thanks,
Sam

carmstrong · March 26, 2014, 12:39am

There is a cookbook for managing sysctl:
http://community.opscode.com/cookbooks/sysctl

You best bet is to depend on and include that cookbook, and then either use
node.default['sysctl']['params']['net']['ipv4']['ip_nonlocal_bind'] = 1

or the LWRP:

sysctl_param 'net.ipv4.ip_nonlocal_bind' do
value 1
end

On Tue, Mar 25, 2014 at 5:23 PM, Sam Su sam.debian@gmail.com wrote:

Hi,

I am trying to change a field (here is "net.ipv4.ip_nonlocal_bind=1") of
the file /etc/sysctl.conf, currently I am using template to change the
field, however someone complained that it was not good to template the
system file ''sysctl.conf', because it may also used by other cookbooks. I
agreed with that guy, it is definitely better to only change a specific
field instead of the whole file with respect to a system file.

I am wondering what is the best way to change a specific field of a config
file in Chef.
It will be much appreciated if someone can give me some hints and share
some opinions.

Thanks,
Sam

carmstrong · March 26, 2014, 12:40am

Mike's solution is the least obtrusive, but if other cookbook authors are
good citizens, they'll be using the sysctl cookbook to edit that file as
well.

On Tue, Mar 25, 2014 at 5:39 PM, Christopher Armstrong <
chris@chrisarmstrong.me> wrote:

There is a cookbook for managing sysctl:
http://community.opscode.com/cookbooks/sysctl

You best bet is to depend on and include that cookbook, and then either
use node.default['sysctl']['params']['net']['ipv4']['ip_nonlocal_bind'] =
1

or the LWRP:

sysctl_param 'net.ipv4.ip_nonlocal_bind' do
value 1
end

On Tue, Mar 25, 2014 at 5:23 PM, Sam Su sam.debian@gmail.com wrote:

Hi,

I am trying to change a field (here is "net.ipv4.ip_nonlocal_bind=1") of
the file /etc/sysctl.conf, currently I am using template to change the
field, however someone complained that it was not good to template the
system file ''sysctl.conf', because it may also used by other cookbooks. I
agreed with that guy, it is definitely better to only change a specific
field instead of the whole file with respect to a system file.

I am wondering what is the best way to change a specific field of a
config file in Chef.
It will be much appreciated if someone can give me some hints and share
some opinions.

Thanks,
Sam

Sam_Su · March 26, 2014, 1:08am

Hi Mike and Christopher,

Great, thank you so much for you guys' help.

I totally agree with Christopher, for my situation the Chef::Util::FileEdit
solution may be better.

Thanks,
Sam

On Tue, Mar 25, 2014 at 5:40 PM, Christopher Armstrong <
chris@chrisarmstrong.me> wrote:

Mike's solution is the least obtrusive, but if other cookbook authors are
good citizens, they'll be using the sysctl cookbook to edit that file as
well.

On Tue, Mar 25, 2014 at 5:39 PM, Christopher Armstrong <
chris@chrisarmstrong.me> wrote:

There is a cookbook for managing sysctl:
http://community.opscode.com/cookbooks/sysctl

You best bet is to depend on and include that cookbook, and then either
use node.default['sysctl']['params']['net']['ipv4']['ip_nonlocal_bind']
= 1

or the LWRP:

sysctl_param 'net.ipv4.ip_nonlocal_bind' do
value 1
end

On Tue, Mar 25, 2014 at 5:23 PM, Sam Su sam.debian@gmail.com wrote:

Hi,

I am trying to change a field (here is "net.ipv4.ip_nonlocal_bind=1") of
the file /etc/sysctl.conf, currently I am using template to change the
field, however someone complained that it was not good to template the
system file ''sysctl.conf', because it may also used by other cookbooks. I
agreed with that guy, it is definitely better to only change a specific
field instead of the whole file with respect to a system file.

I am wondering what is the best way to change a specific field of a
config file in Chef.
It will be much appreciated if someone can give me some hints and share
some opinions.

Thanks,
Sam

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